Spark-plug protector



Jan. 25, A1927,

" J. D. MOORE SPAR-xl PLUG PROTECTOR Filed August 5, 1925 ...l/dx

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Patented Jan. 25, 1927.

Unirse srarss PATENT QFFECE.

SPARK-PLUG ROTECTOR.

Application filed August 3, 1925. Serial No. 47,794.

rlhis invention relates to spark plugs and has tor its object to providea spark plug` protector' of improved construction which will preventfouling oi the ele-xetrodes, without interfering with the proper firingor the cylinder.

rlhe invention will be more clearly understood by reference to theaccompanying drawings in which are shown illustrative embodiments ot theinvention.

In the drawings Fig. 1 is a central vertical section showing a sparkplug provided with a preferred form of protecting device.

Fig. 2 is a similar view showing a inodification, and

Fig. 3 shows a third modii'ication ci the invention.

In Fig. 1 is shown a spark plug which possesses the general featurescommon to nearly all spark plugs of standard type, in* cluding theinsulator 10, central electrode 11, body `iortion 12, threaded as at 17,and the gland 13, suitable gaskets 14- and 15 being employed at thejoints. Side electrodes 162-16 extending from the body portion 12cooperate with the central electrode 11 to produce the spark.

The invention consists in the provision of an attachment designed toprevent oil from reaching the electrodes, and also designed to protectthe insulator from direct contact with the hot` gases in theA maincylinder. As shown in Fig. 1, the attachment comprises a shellinternally threaded at 17 and adapted to be'secured onto the body 12 ofthe spark plug. Y shell is also provided with a nipple 18 which isadapted to be screwed into an engine cylinder. As shown, this shell isprovided with additional side electrodes which are adapted to coact witha reduced portion 2O of the central electrode 11. An important featureof the invention is the provision of a tapered or conical choke member21, integral with the body of the shell and surrounded by the nipple 18which prevents access of oil except through the single reduced orilice22 at the center of the choke member. The chamber 23 formed by the chokemember is an initial combustion chamber in which gas is exploded by thespark ot the upper side electrodes 16 and the central electrode 10.

A second chamber 24 in direct communi- The l cation with the maincoinlnistion chamber is provided below the choke member 21, and a secondspark gap is provided between 'the choke member and the reduced portion20 or' the central electrode. A. third spark lgap is provided within thecombustion chainber proper by button electrodes 19 and the centralelectrode. In this manner, instantaneous tiring oi the entire charge isassured.

It will also be noted that the upper elec* trodes and the insulator arecompletely protected from oil and from the direct heat ot the maincombustion chamber by means of the choke members 21 and that the chokemember itself is partially protected by means of the nipple 18. Byreducing the size of the central electrode, the size of the orifice 22in the choke member may be reduced, whereby greater protection isafforded the upper electrodes and the insulator. Another advantage ofthe present construction is the reduced size of the combustion chamber23 and the short passage connecting the same with the main combustionchamber, thus insuring simultaneous combustion in both chambers. A'further advantage of the reduced size of chamber 23 is the diminishedamount of heat generated therein, whereby all danger of breaking orcracking the insulator is avoided.

The invention is, of course, vsubject to modifications. For example, inFig. 2, I have shown a spark plug having but one side electrode, and aprotecting device in which the lower electrodes are eliminated. Thisdoes away with the necessity for the extension of the central electrode.This device be used under certain circumstances, but the form shown inFig. 1 is preferred.

In Fig. 3 is shown a still further modification. In this constructionthe protecting device is of three parts comprising a sleeve secured tothe body of the spark plug and having a threaded nipple 31 to which issecured a lower sleeve 32 having a nipple 33 designed to be screwed intothe engine cylinder. A separate choke member 34; is held in place by thelower sleeve 32, suitable gaskets 35 being provided. The central oriice36 of the choke member is ot Venturi shape.

Other modifications within the scope of the invention will occur to oneskilled in the art,

Having thus described my invention7 what I claim as new and desire tosecure by Letters Patent isz- The combination with a complete spark plughaving a central electrode, and having a threaded nipple, and sideelectrodes eX- tending inwardly from said threaded nipple an cooperatingWith said central electrode, of a. removable protecting` device for saidelectrodes adapted to be secured to said nipple and having a taperingchoke member extending` inwardly and downwardly from the body ot saidprotecting device and forming an initial combustion chamber enclosingand protecting` said electrodes from access of oil, said choke memberhaving` a single central opening therein and said central electrodehaving an extension of reduced diameter extending through the singleopening` in said choke member, and a protecting cylindrical sleevesurrounding` said choke member and extending substantially below thesame, and forming a second chamber, completely open at the bottom butserving to prevent lateral access of oil to the initial combustionchamber, said sleeve having supplemental side electrodes cooperatingwith the reduced portion of the central electrode, whereby a spark isproduced directly in the main combustion chamber of an internalcombustion engine.

In testimony whereof- I affix my siggjnature.

JOHN D. MOORE.

